This invention relates to catalysts, catalyst systems and methods of production of olefin polymers, including isotactic, syndiotactic and stereoblock polymer, and the polymers produced thereby.
The mechanical properties of a given polymer can generally be classified as rigid, flexible, or elastic. While metallocene catalysts are capable of producing polymers that fall into each of these classifications, the most intense efforts have been directed at surpassing existing systems in their aptitude for making rigid isotactic polypropylene and rigid or flexible polyethylene [1] More recently, growing efforts to devise metallocene catalysts capable of producing elastomeric polymers have revealed several different viable strategies: ethylene/xcex1-olefin copolymers [2]; high molecular weight atactic polypropylene [3]; binary isotactic/atactic compatibilized polypropylene [4]; isotactic-atactic polypropylene [5]; stereoblock isotactic-atactic polypropylene [6]; and isotactic polypropylene with controllable stereoerror sequences. [7] Although the structure/property relationship of each of these regimes is not fully understood, the elastomeric properties undoubtedly rely on the existence of physical crosslinks in the presence of an amorphous phase. In the case of high molecular weight materials, the crosslinks can be simple chain entanglements. In the other examples, segments from several different polymer chains participate in crystalline regions, which physically connect the chains and provide crosslinks in an otherwise amorphous phase.
One of the best understood systems is that initially developed by Coates and Waymouth. [6, 8] Their unbridged metallocene (2-phenylindenyl)2ZrCl2, in the presence of methylaluminoxane (MAO), isomerizes between chiral and achiral coordination geometries during the formation of a given polypropylene chain. Since the chiral isomer is isospecific and the achiral isomer is aspecific, stereoblock isotactic-atactic polypropylene is obtained.
Elastomeric and other polyolefins with controlled stereostructures are useful for a wide variety of applications. Novel polyolefins, especially those with elastomeric properties, can be useful for a wide variety of applications. Accordingly, there is a need for catalyst systems capable of polymerizing alkenes to novel polyolefins.
There is also a need to develop catalysts sufficiently stable to be used on an industrial scale. Owing to the chelate effect, bridged metallocene catalysts tend to be more stable at elevated polymerization temperatures, and often behave more predictably when adsorbed on a support, a common industrial tactic.
Accordingly, there is a need for stable, readily synthesized catalyst systems capable of controlled polymerization of alkenes to give polyolefins.
The invention provides bridged metallocene catalyst systems that are useful for the controlled polymerization of alkenes to polyolefins. Also provided are catalyst systems useful for polymerizing a variety of alkene monomers into stereocontrolled polymers including isotactic polymers, syndiotactic polymers and stereoblock polymers containing both hemiisotactic and isotactic regions. Catalysts of the invention can be chosen to provide a specific size range of produced polymers. Catalysts also can be chosen so as to produce a polymer with a desired microstructure.
This invention describes a new catalyst system for polymerizing C2 to C10 alk-1-enes to produce polyolefin polymers. The catalyst system includes two components: (a) an organometallic compound of the general formula (II), 
in which M is a metal of the III, IV, or V subgroup of the periodic system or a metal from the lanthamide or actinide groups; X is fluorine, chlorine, bromine, iodine, hydrogen, C1 to C10 alkyl, C6 to C20 aryl, alkylaryl, arylalkyl, fluoroalkyl, or fluoroaryl having 1 to 10 20 carbons in the alkyl moiety and 6 to 20 carbon atoms in the aryl moiety, or xe2x80x94OR17 where R17 is a C1 to C10 alkyl or C6 to C20 aryl; n is the formal oxidation state of M minus 2; E1 is hydrogen, carbon, silicon, or germanium; E2 is carbon, silicon, or germanium; R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, R15, and R16 are, independently, hydrogen, C1 to C10 alkyl, 3 to 10 membered cycloalkyl, which in turn may have from 1 to 10 C1 to C10 alkyls as substituents, C6 to C16 aryl or arylalkyl in which two adjacent substituents may together stand for cyclic groups having 4 to 16 carbon atoms which in turn may be substituted, or Si(R18)3 where R18 is a C1 to C10 alkyl, C6 to C16 aryl or C3 to C10 cycloalkyl; and where E1 is hydrogen, R1, R2 and R3 are absent; or an organometallic compound of the general formula (III), 
in which M is a metal of the III, IV, or V subgroup of the periodic system or a metal from the lanthamide or actinide groups; X is fluorine, chlorine, bromine, iodine, hydrogen, C1 to C10 alkyl, C6 to C20 aryl, alkylaryl, arylalkyl, fluoroalkyl, or fluoroaryl having 1 to 10 carbons in the alkyl moiety and 6 to 20 carbon atoms in the aryl moiety, or xe2x80x94OR13 where R13 is a C1 to C10 alkyl or C6 to C20aryl; n is the formal oxidation state of M minus 2; E1 is hydrogen, carbon, silicon, or germanium; E2 is carbon, silicon, or germanium; R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, and R12 are, independently, hydrogen, C1 to C10alkyl, 3 to 10 membered cycloalkyl, which in turn may have from 1 to 10 C1 to C10 alkyls as substituents, C6 to C16 aryl or arylalkyl in which two adjacent substituents may together stand for cyclic groups having 4 to 16 carbon atoms which in turn may be substituted, or Si(R14)3 where R14 is a C1 to C10 alkyl, C6 to C16 aryl or C3 to C10 cycloalkyl; and where E1 is hydrogen, R1, R2 and R3 are absent; and (b) an activator.
Catalyst System for Isotactic Polyolefins
Metallocene catalysts can be chosen according to the invention that produce isotactic polyolefins. The preferred catalyst for polymerizing C2 to C10 alk-1-enes to produce isotactic polyolefins is compound II or compound III wherein no elements of symmetry exist; that is, compound II or compound III are of C, symmetry. It is generally preferred that the R1, R2, R3, and E1 group is a sterically large group, for example an adamantyl group. The preferred metals are titanium, zirconium, hafnium, scandium, and yttrium. The preferred X are chlorine, bromine, hydrogen, methyl, phenyl, and benzyl. The preferred E2 is carbon or silicon. The preferred R substituents are as follows: For II, R1, R2, R3, and E1 constitute the 2-methyl-2-adamantyl group; R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 are hydrogen; R15 and R16 are methyl, phenyl, or part of a cycloalkyl group, including cyclohexyl or adamantyl. For III, R1, R2, R3, and E1 constitute the 2-methyl-2-adamantyl group; R4, R5, R6, R7, R8, R9, and R10 are hydrogen; R11 and R12 are methyl, phenyl, or part of a cycloalkyl group, including cyclohexyl or adamantyl.
Catalyst System for Syndiotactic Polyolefins
Catalyst systems also can be prepared that preferentially catalyze the formation of syndiotactic polyolefins from alkene precursors. The preferred catalyst for polymerizing C2 to C10 alk-1-enes to produce syndiotactic polyolefins is compound III wherein a mirror plane of symmetry exists; that is, compound III is of Cs symmetry. The preferred metals are titanium, zirconium, hafiium, scandium, and yttrium. The preferred X are chlorine, bromine, hydrogen, methyl, phenyl, and benzyl. The preferred E1 is carbon or silicon. The preferred R substituents are as follows: E1 is hydrogen, R1, R2 and R3 are absent; R4, R5, R6, R7, R8, R9 and R10 are hydrogen; R11 and R12 are methyl, phenyl, or part of a cycloalkyl group, including cyclohexyl or adamantyl.
Catalyst System for Elastomeric Polyolefins
The preferred catalyst for polymerizing C2 to C10 alk-1-enes to produce stereoblock isotactic-hemiisotactic polyolefins is compound II wherein there are no symmetry elements; that is, compound II is of C1 symmetry. The preferred metals are titanium, zirconium, hafnium, scandium, and yttrium. The preferred X are chlorine, bromine, hydrogen, methyl, phenyl, and benzyl. The preferred E1 and E2 are carbon and silicon. The preferred R substituents are as follows: R1 is hydrogen; R2, and R3 are, independently, hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, trimethylsilyl, or part of a cycloalkyl group, including cyclohexyl, adamantyl, or 3,3,5,5-tetramethylcyclohexyl; R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, and R14 are hydrogen or methyl; and R15 and R16 are hydrogen, methyl, or phenyl.
Polyolefin Polymerization
The metallocenes of the present invention, in the presence of appropriate activators, are useful for the polymerization of alkenes, including ethylene and alpha-olefins, for example propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene and combinations thereof. The polymerization of olefins is carried out by contacting the olefin with the catalyst systems comprising the transition metal component and in the presence of an appropriate cocatalyst, for example an alumoxane, or a Lewis acid for example B(C6F5)3, or a protic acid containing a non-coordinating anion, for example [PhNMe2H]+B(C6F5)4xe2x88x92. Conditions suitable for the polymerization of olefins to polyolefins are known in the art. Suitable temperatures, pressures, and optional solvents can be determined by one of skill in the art for use in the present invention.
The metallocene catalyst systems of the present invention are useful for the polymerization of alkenes to polyolefins. In particular, catalysts can be selected to produce isotactic or syndiotactic polypropylene. Examples of catalysts suitable for the production of a particular type of catalyst are given above and in the following Examples. In one embodiment, the alkenes to be polymerized are alpha olefins.
The metallocene catalyst systems of the present invention are particularly useful for the polymerization of propylene to produce polypropylenes with novel elastomeric properties. By elastomeric, we mean a material which tends to regain its shape upon extension, or one which exhibits a positive power of recovery at 100%, 200% and 300% elongation. The properties of elastomers are characterized by several variables. The initial modulus is the resistance to elongation at the onset of stretching. This quantity is simply the slope at the beginning of the stress-strain curve. Upon overstretching, the polymer sample eventually ruptures. The rupture point yields two important measurements, the tensile strength (Tb) and the ultimate elongation (Eb). These values are the stress and percent elongation at the break, respectively. The tensile set (TS) is the elongation remaining in a polymer sample after it is stretched to 300% elongation and allowed to recover. An additional measure of the reversibility of stretching is the percent recovery (PR), which is given by the equation: 100(final lengthxe2x88x92initial length)/(initial length).
It is believed that the elastomeric properties of the polypropylenes of this invention are due to an alternating block structure comprising of isotactic and hemiisotactic stereosequences. Without being bound by theory, it is believed that isotactic block stereosequences provide crystalline blocks which can act as physical crosslinks in the polymer network.
The structure of the polymer can be described in terms of the isotactic pentad content [mmmm] which is the percentage of isotactic stereosequences of 5 contiguous stereocenters, as determined by 13C NMR spectroscopy (Zambelli, A. et al. 1975. Macromolecules 8, 687-689). The isotactic pentad content of statistically atactic polypropylene is approximately 6.25%, while that of highly isotactic polypropylene can approach 100%. Polymers also can be characterized for their isotactic percent (m).
While it is possible to produce polypropylenes with a range of isotactic pentad contents, the elastomeric properties of the polymer will depend on the distribution of isotactic (crystalline) and atactic (amorphous) stereosequences. Thermoplastic elastomers consist of amorphous-crystalline block polymers, and thus the blockiness of the polymer determines whether it will be elastomeric.
The structure, and therefore the properties of the obtained polypropylenes also depend on the nature of the ligand bound to the transition metal.
It will be appreciated from the illustrative examples that this catalyst system provides an extraordinary broad range of polymer properties from the polymerization process of this invention.
Polyolefins can be obtained by suitable manipulation of the metallocene catalyst, the reaction conditions, or the cocatalyst to give polymers which range in properties from gum elastomers to thermoplastic elastomers to flexible thermoplastics, and indeed, to relatively rigid thermoplastics.
The polymers of the present invention in one embodiment are a novel class of thermoplastic elastomers made up of propylene homopolymers of weight average molecular weights ranging from 20,000 to above about 2 million. Preferably, the average molecular weights of the polypropylenes are very high, as molecular weights on the average of 1,000,000 are readily obtainable and even higher Mw are indicated. The molecular weight distributions of the polymers are quite low, with typical polydispersities, Mw/Mn, ranging from about 1.8 to about 4.4, and more preferably can be controlled to be in the range of about 1.8 to about 2.4. However, by control of reaction conditions, higher molecular weight distributions also can be obtained, e.g., polydispersities of 5-20 are easily produced. The elastomeric polypropylenes of the present invention have isotactic pentad contents ranging from an [mmmm] content of about 25% to an [mmmm] of about 50%. The polypropylenes of the present invention range from amorphous atactic polypropylenes with no melting point, to elastomeric polypropylenes of high crystallinity with melting points up to about 160xc2x0 C.
Accordingly, because of the wide range of structures and crystallinities, the polypropylenes of the present invention exhibit a range of properties from gum elastomers, to thermoplastic elastomers, to flexible thermoplastics. The range of elastomeric properties for the polypropylenes is quite broad. Properties of particular polymers of the invention are listed in the Tables.
The polypropylenes of the present invention can be melt spun into fibers, or can be cast into transparent, tough, self-supporting films with good elastic recoveries. Thin films of elastomeric polypropylenes with isotactic pentad contents [mmmm]=30% are slightly opaque, but exhibit stress-whitening upon extension, which may be indicative of stress-induced crystallization. The elastomeric polypropylenes can also be cast into molded articles.
The elastomeric polypropylenes of the present invention can be blended with isotactic polypropylenes, including isotactic polypropylenes of the invention. The melting points and heats of fusion of the blends increase steadily with increasing mole fraction of isotactic polypropylene in the blend.
The utility of the polymers of the present invention are evident and quite broad, including films, adhesives, resilient and elastomeric objects. As they are completely compatible with isotactic polypropylene, they are ideal candidate additives to improve the toughness and impact strength of isotactic polypropylenes.
Isotactic Polyolefins
This invention describes a new material synthesized from C2 to C10 alk-1-enes by a catalyst system. The polymer formed is a thermoplastic [1] and has the general microstructure and tacticity depicted by formula (IV): 
in which R1 is C1 to C8 alkyl, 3 to 10 membered cycloalkyl, C6 to C20 aryl, alkylaryl, arylalkyl, fluoroalkyl, or fluoroaryl having 1 to 10 carbons in the alkyl moiety and 6 to 20 carbon atoms in the aryl moiety, Si(R4)3 where R4 is a C1 to C10 alkyl, or xe2x80x94OR5 where R5 is hydrogen, C1 to C10 alkyl or C6 to C20 aryl; R2 and R3 are independently hydrogen, C1 to C10 alkyl, C2 to C10 alkenyl, or OR5; n is greater than 0.
The preferred isotactic polymer structure is polyolefin IV wherein R1 is methyl, R2 is hydrogen, ethenyl, isopropyl, or isopropenyl, and R3 is hydrogen or methyl. The preferred n is greater than 0. The preferred polymer tacticity is thus isotactic. The preferred thermo-mechanical properties of the polymer are those of a thermoplastic.
This new polymer may be prepared via monomer polymerization processes that occur homogeneously in solution, supported in a solution, in the gas phase, at high pressure, or in bulk monomer, including the condensed phase of lower molecular weight alk-1-enes. The preferred processes are bulk monomer and gas phase polymerization methods. Catalyst systems may be organometallic compounds containing a metal of the III, IV, or V subgroup of the periodic system, or a metal from the lanthamide or actinide groups, activated by systems which may be alkylaluminums, haloalkylaluminums, alkylaluminoxanes or ionic activators. The preferred organometallic precatalysts are (methyl)2C(3-(2-methyl-2-adamantyl)cyclopentadienyl) (fluorenyl) zirconium dichloride (71, xe2x80x9cR2C(Cp1)(Flu1)zirconium dichloridexe2x80x9d) and (methyl)2C(3-(2-methyl-2-adamantyl)cyclopentadienyl) (octamethyloctahydrodibenzofluorenyl) zirconium dichloride (72, xe2x80x9cR2C(Cp2)(Oct1)zirconium dichloridexe2x80x9d). The preferred activators are methylaluminoxane and activators which contain boron. 
Most preferably, the produced polyolefin will be a high melting thermoplastic. Polymerization of two or more monomers may be employed to produce copolymers or terpolymers. Combinations of two or more metallocene catalyst precursors may be used to prepare a blend of polymers. The polymers, copolymers, and terpolymers prepared according to this invention may be blended with existing, commercial polyolefins.
Isotactic polymers produced with the catalysts of the invention have catalytic dyad (mm) contents of at least about 98% and can have mm content of  greater than 99%. Catalysts of the invention are particularly suited to the production of isotactic polypropylene.
Syndiotactic Polyolefins
This invention also describes a new material synthesized from C2 to C10 alk-1-enes by a catalyst system. The polymer formed is a thermoplastic1,2 and has the general microstructure and tacticity depicted by formula (I) 
in which R1 is C1 to C8 alkyl, 3 to 10 membered cycloalkyl, C6 to C20 aryl, alkylaryl, arylalkyl, fluoroalkyl, or fluoroaryl having 1 to 10 carbons in the alkyl moiety and 6 to 20 carbon atoms in the aryl moiety, Si(R4)3 where R4 is a C1 to C10 alkyl, or xe2x80x94OR5 where R5 is hydrogen, C1 to C10 alkyl or C6 to C20 aryl; R2 and R3 are independently hydrogen, C1 to C10 alkyl, C2 to C10 alkenyl, or oR5; n is greater than 0.
The preferred polymer structure is polyolefin V wherein R1 is methyl, R2 is hydrogen, ethenyl, isopropyl, or isopropenyl, and R3 is hydrogen or methyl. The preferred n is greater than 0. The preferred polymer tacticity is thus syndiotactic. The preferred thermo-mechanical properties of the polymer are those of a thermoplastic.
Method of Preparing Syndiotactic Polyolefins
This new polymer may be polymerized via monomer polymerization processes that occur homogeneously in solution, supported in a solution, in the gas phase, at high pressure, or in bulk monomer, including the condensed phase of lower molecular weight alk-1-enes. The preferred processes are bulk monomer and gas phase polymerization methods. Catalyst systems may be organometallic compounds containing a metal of the III, IV, or V subgroup of the periodic system, or a metal from the lanthamide or actinide groups, activated by systems which may be alkylaluminums, haloalkylaluminums, alkylaluminoxanes or ionic activators. The preferred organometallic precatalysts are (methyl)2C(cyclopentadienyl) (octamethyloctahydrodibenzofluorenyl)zirconium dichloride (91) and (phenyl)2C(cyclopentadienyl)(octamethyloctahydrodibenzofluorenyl)zirconium dichloride (92). The preferred activators are methylaluminoxane and activators which contain boron.
Most preferably, the produced polyolefin will be a high melting thermoplastic. Polymerization of two or more monomers may be employed to produce copolymers or terpolymers. Combinations of two or more metallocene catalyst precursors may be used to prepare a blend of polymers. The polymers, copolymers, and terpolymers prepared according to this invention may be blended with existing, commercial polyolefins.
Elastomeric Polyolefins
This invention describes a new material synthesized from C2 to C10 alk-1-enes by a catalyst system. The polymer formed is a thermoplastic elastomer1 and has the general microstructure and tacticity depicted by formula (Z) 
in which R1 is C1 to C8 alkyl, 3 to 10 membered cycloalkyl, C6 to C20 aryl, alkylaryl, arylalkyl, fluoroalkyl, or fluoroaryl having 1 to 10 carbons in the alkyl moiety and 6 to 20 carbon atoms in the aryl moiety, Si(R4)3 where R4 is a C1 to C10 alkyl, or xe2x80x94OR5 where R5 is hydrogen, C1 to C10 alkyl or C6 to C20 aryl; R2 and R3 are independently hydrogen, C1 to C10 alkyl, C2 to C10 alkenyl, or OR5; m, n, and p are each greater than 0.
The preferred elastomeric polymer structure is polyolefin VI wherein R1 is methyl, R2 is hydrogen, ethenyl, isopropyl, or isopropenyl, and R3 is hydrogen or methyl. The preferred m is greater than 5 but less than 50% of the degree of polymerization, which is given by (P)xc2x7(maverage+2naverage). The preferred n is greater than 5 but less than 25% of the degree of polymerization. The preferred p is greater than 0. The preferred polymer tacticity is thus stereoblock isotactic-hemiisotactic. The preferred therno-mechanical properties of the polymer are those of a thermoplastic elastomer.
This new polymer may be polymerized via monomer polymerization processes that occur homogeneously in solution, supported in a solution, in the gas phase, at high pressure, or in bulk monomer, including the condensed phase of lower molecular weight alk-1-enes. The preferred processes are bulk monomer and gas phase polymerization methods. Catalyst systems may be organometallic compounds containing a metal of the III, IV, or V subgroup of the periodic system, or a metal from the lanthamide or actinide groups, activated by systems which may be alkylaluminums, haloalkylaluminums, alkylaluminoxanes or ionic activators. The preferred organometallic precatalysts are (methyl)2C(3-(2-adamantyl)cyclopentadienyl) (fluorenyl)zirconium dichloride (91) and (phenyl)2C(3-(2-adamantyl)cyclopentadienyl) (fluorenyl)zirconium dichloride (92). The preferred activators are methylaluminoxane and activators which contain boron.
Most preferably, the produced polyolefin will be a thermoplastic elastomer containing alternating isotactic and hemiisotactic stereoblocks. Polymerization of two or more monomers may be employed to produce copolymers or terpolymers. Combinations of two or more metaliocene catalyst precursors may be used to prepare a blend of polymers. The polymers, copolymers, and terpolymers prepared according to this invention may be blended with existing, commercial polyolefins.
Activators
Appropriate activators for use with the metallocene catalysts of the invention include alkylaluminum compounds, methylaluminoxane, or modified methylaluminoxanes of the type described in the following references: U.S. Pat. No. 4,542,199 to Kaminsky, et al; Ewen, J. Am. Chem. Soc., 106 (1984), p. 6355; Ewen, et al., J. Am. Chem. Soc. 109 (1987) p. 6544; Ewen, et al, J. Am. Chem. Soc. 110 (1988), p. 6255.; Kaminsky, et al., Angew. Chem., Int. Ed. Eng. 24 (1985), p. 507. Other cocatalysts which may be used include Lewis or protic acids, which generate cationic metallocenes with compatible non-coordinating anions for example B(C6F5)3 or [PhNMe2H]+B(C6F5)xe2x88x924 in the presence or absence of alkylaluminum compounds. Catalyst systems employing a cationic Group 4 metallocene and compatible non-coordinating anions are described in European Patent Applications 277,003 and 277,004 filed on 27.01.88 by Turner, et al.; European Patent Application 427,697-A2 filed on 09.10.90 by Ewen, et al.; Marks, et al., J. Am. Chem. Soc., 113 (1991), p. 3623; Chien et al., J. Am. Chem. Soc., 113 (1991), p. 8570; Bochman et al., Angew. Chem. Intl. Ed. Engl. 7 (1990), p. 780; and Teuben et al., Organometallics, 11 (1992), P. 362, and references therein.
Utility
As thermoplastics, these new materials may be processed via methods including injection molding, extrusion, or blow molding and may have applications that take advantage of its mechanical behavior and mechanical properties, including its tensile strength, rigidity and impact strength. Additional properties of this material may include recyclability, chemical resistivity, thermal stability, electrical conductivity, optical transparency, and processability.
Definitions
The term xe2x80x9calkylxe2x80x9d as used herein refers to a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl and the like, as well as cycloalkyl groups for example cyclopentyl, cyclohexyl and the like. The term xe2x80x9clower alkylxe2x80x9d intends an alkyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Alkyl substituents includes optionally substituted.
The term xe2x80x9ccycloalkylxe2x80x9d as used herein refers to a cyclic hydrocarbon of 4 to 10 carbon atoms forming a ring, including bicyclic systems.
The term xe2x80x9csubstituted cycloalkylxe2x80x9d as used herein refers to a cycloalkyl ring having substituents on said ring of alkyl, alkoxy, xe2x80x9cSubstituted cycloalkylxe2x80x9d includes substitution with from 1 to 10 carbons at each ring position, with a total number of carbon substitutions in the range of 1 to 30.
A xe2x80x9ccyclic groupxe2x80x9d is a ring composed of 4 to 10 atoms selected from carbon, silicon, oxygen, sulfur, selenium, and germanium.
The term xe2x80x9calkoxyxe2x80x9d as used herein intends an alkyl group bound through a single, terminal ether linkage; that is, an xe2x80x9calkoxyxe2x80x9d group may be defined as xe2x80x94OR where R is alkyl as defined above. A xe2x80x9clower alkoxyxe2x80x9d group intends an alkoxy group containing one to six, more preferably one to four, carbon atoms.
The term xe2x80x9carylxe2x80x9d as used herein refers to an aromatic species containing 1 to 5 aromatic rings, either fused or linked, and either unsubstituted or substituted with 1 or more substituents typically selected from the group consisting of xe2x80x94(CH2)xxe2x80x94NH2, xe2x80x94(CH2)xxe2x80x94COOH, xe2x80x94NO2, halogen and lower alkyl, where x is an integer in the range of 0 to 6 inclusive as outlined above. Preferred aryl substituents contain 1 to 3 fused aromatic rings, and particularly preferred aryl substituents contain 1 aromatic ring or 2 fused aromatic rings. The term xe2x80x9caralkylxe2x80x9d intends a moiety containing both alkyl and aryl species, typically containing less than about 24 carbon atoms, and more typically less than about 12 carbon atoms in the alkyl segment of the moiety, and typically containing 1 to 5 aromatic rings. The term xe2x80x9caralkylxe2x80x9d will usually be used to refer to aryl-substituted alkyl groups. The term xe2x80x9caralkylenexe2x80x9d will be used in a similar manner to refer to moieties containing both alkylene and aryl species, typically containing less than about 24 carbon atoms in the alkylene portion and 1 to 5 aromatic rings in the aryl portion, and typically aryl-substituted alkylene. Exemplary aralkyl groups have the structure xe2x80x94(CH2)jxe2x80x94Ar wherein j is an integer in the range of 1 to 24, more typically 1 to 6, and Ar is a monocyclic aryl moiety.
xe2x80x9cHaloxe2x80x9d or xe2x80x9chalogenxe2x80x9d refers to fluoro, chloro, bromo or iodo, and usually relates to halo substitution for a hydrogen atom in an organic compound. Of the halos, chloro and fluoro are generally preferred.
xe2x80x9cHydrocarbylxe2x80x9d refers to unsubstituted and substituted hydrocarbyl radicals containing 1 to about 20 carbon atoms, including branched or unbranched, saturated or unsaturated species, for example alkyl groups, alkenyl groups, aryl groups, and the like. The term xe2x80x9clower hydrocarbylxe2x80x9d intends a hydrocarbyl group of one to six carbon atoms, preferably one to four carbon atoms.
xe2x80x9cOptionalxe2x80x9d or xe2x80x9coptionallyxe2x80x9d means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase xe2x80x9coptionally substituted alkylxe2x80x9d means that an alkyl moiety may or may not be substituted and that the description includes both unsubstituted alkylene and alkylene where there is substitution.
Substitution of an alkyl, aryl or other hydrocarbon means that a hydrogen of the hydrocarbon is substituted with another atom or group of atoms. Such atoms include halogens. Groups of atoms can by alkyl substituents, aryl substituents, aralkyl, alkoxy and the like substituents.
Methods of Preparing Catalysts
Metallocenes Containing the Fluorene Ligand
Substituted fulvene [Fulvene1] can be prepared by known methods. The anion [Flu1]xe2x88x92 is prepared by treatment of [Flu1]H with alkali metal-alkyls or Grignard reagents in a solvent to give the corresponding substituted fluorenyl anion. 
In a solvent, R15R16E2(Flu1H)(Cp1H) is formed by combining [Fulvenel] and [Flu1]xe2x88x92, followed by quenching with a proton source, for example water. 
The dianion of R15R16E2(Flu1H)(Cp1H) is formed by treatment with alkali metal-alkyls or Grignard reagents in a solvent: [R15R16E2(Flu1)(Cp1)]xe2x88x922. Reaction of this dianion with MXn+2 in a solvent produces compound (II), which is isolated according to known methods.
Metallocenes Containing the Octamethyloctahydrodibenzofluorene Ligand
1,1,4,4,7,7,10,10-octamethyl-1,2,3,4,7,8,9,10-octahydro dibenzo[b, h] fluorene (OctH) is prepared by the reaction of two equivalents of 2,5-dichloro-2,5-dimethylhexane with one equivalent of fluorene in a solvent in the presence of a Friedel-Crafts initiator. 
Substituted fulvene [Fulvene 2] can be prepared by known methods. The anion [Oct1]xe2x88x92 is prepared by treatment of [Oct1]H with alkali metal-alkyls or Grignard reagents in a solvent to give the corresponding substituted octamethyloctahydrodibenzofluorenyl anion. 
In a solvent, R11R12E2(Oct1H)(Cp2H) is formed by combining [Fulvene2] and [Oct1]xe2x88x92, followed by quenching with a proton source, for example water. 
The dianion of R11R12E2 (Oct1H)(Cp2H) is formed by treatment with alkali metal-alkyls or Grignard reagents in a solvent: [R11R12E2(Oct1)(Cp2)]xe2x88x922. Reaction of this dianion with MXn+2 in a solvent produces compound (III), which is isolated according to known methods.